ABSTRACT
This chapter enchants by the mutation and selection technique and exploits the host-vector systems of amino acid-producing bacteria, because a host-vector system is an ultimate tool for the application of recombinant DNA technology to the organisms of interest. The usefulness of recombinant DNA technology in the breeding of amino acid producers has been demonstrated by the production of threonine, lysine, and tryptophan by recombinant Escherichia coli strains. The chapter introduces the efforts made in construction of host-vector systems for amino acid-producing coryneform bacteria, such as Brevibacterium lactofermentum and Corynebacterium glutamicum and the application of host-vector systems for gene analysis and breeding of amino acid producers. A host-vector system consists of three major parts: a transformation method for DNA incorporation into the cell, vectors as carrier for gene(s) of interest, and host cells as the DNA recipient. By using electroporation and protoplast regeneration systems, a DNA fragment can be introduced into coryneform bacterial cells rather easily.
